Apparatus for graining plates

ABSTRACT

Apparatus for graining aluminum lithographic plates comprising a vacuum table adapted to hold plates to be grained thereon by vacuum, and to be oscillated in level position with steel balls thereon in a slurry for graining the exposed faces of the plates. The table carries a ball hopper at one end thereof, and is tiltable from its level graining position to a ball-unloading position inclined downward toward this end for gravity discharge of balls from the table to the hopper, and also to a ball-loading position inclined downward away from this end for delivery of balls from the hopper to the table, with the hopper swingable between a ball-receiving position and a ball-delivery position relative to the table.

United States Patent [191 Harrell et al. Jan. 1, 1974 APPARATUS FORGRAINING PLATES 3,004,766 10/1961 Bryant 51/235 3 l 9 9 1 [75]Inventors: Robert E. Harrell, Manchester; Roy 149 l 63 Flowers eta]51/235 C. Bax; Leonard P. Kumpf, both of FOREIGN PATENTS OR APPLICATIONSS LOuis; Donald Toliver, 926,472 3/1955 Germany 51/6 Bridgeton, all ofMo.

[73] Assignee: Western Litho Plate & Supply Co., P y Examinerchal'lesLanham St. Louis, Mo. Assistant Examiner-E. M. Combs At! -l( ni Se nier, Power & Lea itt 221 Filed: May 5, 1971 g n g S V [21] App]. No.:140,333 57 ABSTRACT Apparatus for graining aluminum lithographic plates[52] US. Cl. 51/6 omprising a vacuum table adapted to hold plates to[51] hit. Cl 1324b 19/00 be grained thereon by vacuum, and to beoscillated in Fleld of Search level position with steel balls thereon ina slurry for 51/235 graining the exposed faces of the plates. The tablecarries a ball hopper at one end thereof, and is tiltable ReferencesClted from its level graining position to a ball-unloading po- UNITEDSTATES PATENTS sition inclined downward toward this end for gravity1,199,028 9/1916 Cornwall 51/6 discharge of balls from the table to thehopper and 1900 090 3 1933 Becket! n 5 1 also to a ball-loading positioninclined downward away 1,925,963 9/1933 H k 51/6 from this end fordelivery of balls from the hopper to 1,960,447 6/1934 Mctrick 51/6 thetable, with the hopper swingable between a ball- 2,225.752 12/1940Mertes t a! receiving position and a ball-delivery position relative2,413,898 1/1947 Zarkin 51/6 to the table 3.579.916 5/[971 Boettcher....5l/235 2,074,633 3/1937 Zarkin 51/6 3 Claims, 17 Drawing FiguresPATENTEUJAN' H914 SHEET 3 0F 7 FIG.6

FIG.7

PATENTEDJAN um SHE" 7 0% 7 APPARATUS FOR GRAINING PLATES BACKGROUND OFTHE INVENTION This invention relates to apparatus for graining plates,and more particularly to apparatus for graining aluminum lithographicplates.

Plates of sheet aluminum coated on one face with a light-sensitivematerial are widely used as lithographic plates in lithographic printingoperations. For best results, it is desirable that such plates beprepared for the application of the coating with a special finish orgrain on the stated face. One type of apparatus which has been used forabrading the faces of aluminum plates to provide a suitable graincomprises an oscillatory table on which plates are clamped down andtheir upper surfaces abraded by means of steel balls and an abrasiveslurry on'the table (which has a rim'for holding the slurry and theballs thereon). While this type of apparatus has been generallysatisfactory so far as the end result (i.e., grained plates) isconcerned, it takes considerable time to clamp the plates to the table,to load the table with the balls, unload the balls for removal of theplates, and to unclamp and remove the plates. Also, the capacity of atable for plates of different sizes and gage-thickness is limited.

SUMMARY OF THE INVENTION Among the several objects of this invention maybe noted the provision of improved plate graining apparatus of thegeneral class above described in which loading, distribution andunloading of the balls are automatically and relatively rapidly andefficiently effected; the provision of such apparatus in which the ballsare effectively automatically cleaned and undersized balls automaticallyremoved (as is desirable noting that undersized balls would have atendency to gather in various areas of the table and adversely affectthe quality of the plates where they have gathered); the provision ofsuch apparatus in which the placement and securement of plates on thetable is expedited, and in which plates of various sizes and thicknessmay be readily placed and secured and removed, with maximum utilizationof the area of the table.

In general, apparatus made in. accordance with this invention comprisesa table adapted to be oscillated in level position with balls in aslurry thereon for graining plates held on the table. A hopper for theballs is provided at one end of the table. The table is mounted forbeing tilted from its said level position to a ballunloading positioninclined downwardly toward its said hopper end for gravity discharge ofballs from the table to the hopper, and also for being tilted to aball-loading position inclined downwardly away from its said hopper endfor gravity delivery of balls from the hopper to the table, means beingprovided for effecting tilting of the table either to its saidball-unloading position or its ball-loading position. Other objects andfeatures will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation ofapparatus made in accordance with this invention;

FIG. 2 is a vertical longitudinal section of the apparatus, with partsbroken away and omitted at the left end of the view;

FIG. 3 is an enlarged fragment of FIG. 2;

FIG. 4 is a plan of part of the apparatus at its hopper end on a largerscale than FIGS. 1 and 2;

FIG. 5 is a vertical section on line 5-5 of FIG. 4;

FIG. 6 is a plan of part of the apparatus at its opposite end on thesame scale as FIGS. 1 and 2, the view being turned 90;

FIG. 7 is an end view of the apparatus as viewed from its right end inFIG. 1 (the lower end of FIG. 6);

FIG. 8 is a diagrammatic view showing the various positions of the tableand hopper of the apparatus, and showing the operating cylinders andvalves of the apparatus;

FIG. 9 is a vertical longitudinal section on line 9-9 of FIG. 10;

FIG. 10 is a vertical transverse section on line 10-10 of FIG. 1;

FIGS. 11 and 12 are enlarged views showing certain lock members inclosed (FIG. 11) and open (FIG. 12) position;

FIGS. 13A, B and C together constitute a wiring diagram;

FIG. 14 is a vertical section of a ball stand of the apparatus; and

FIG. 15 is a chart showing the programming of a stepping switch of theapparatus.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, firstmore particularly to FIGS. 1-4, apparatus made in accordance with thisinvention for graining plates, and particularly sheet aluminum plates tobe used as lithographic plates, is shown to comprise a vacuum tablegenerally designated 1 adapted by means of vacuum to hold plates thereonto be grained, as will appear. The plates to be grained are indicated at2 in FIG. 3. The table is adapted to be oscillated in level position (asshown in FIGS. 1 and 2 and as indicated at TL in FIG. 8) with steelballs 3 (which may be inch in diameter or less) in an abrasive slurrythereon for graining the exposed upper faces of the plates 2 held on thetable. The balls are omitted in FIGS. 2, 4 and 5. There are a largenumber of balls, generally sufficient, when the balls are spread out ina double layer, to cover the entire table. A hopper for the ballsgenerally designated 4 is provided at one end of the table, which endmay be referred to as its hopper or head end, and oscillates with thetable. The table is mounted, as will appear, for being tilted from itslevel position to a ball-unloading position inclined downward toward itshopper end, as indicated at BU in FIG. 8, for gravity discharge of ballsfrom the table to the hopper, and also for being tilted to aball-loading position as indicated at BL in FIG. 8 inclined downwardlyaway from its said hopper end for gravity delivery of balls from thehopper to the table. The hopper is pivotally mounted on the table forbeing swung from the lowered level position relative to the table inwhich it is shown in solid lines in FIGS. 1 and 8 to the raised uptilted position relative to the table illustrated in phantom at HR inFIGS. 1 and 8.

The table 1 is of elongate rectangular shape in plan. It is mounted onan oscillable elongate rectangular horizontal carriage generallydesignated 5 which includes a pair of intermediate longitudinal bars 7(see FIGS. 2

and 6) on opposite sides of its longitudinal center line, a pair ofoutside longitudinal bars 9 spaced outward from the intermediatelongitudinal beams 7, and transversely extending end bars 11 and 13.Each of these bars is of hollow rectangular cross section. The side bars9 of this carriage have hardened steel pads such as indicated at 15 ontheir bottoms spaced at intervals along the length of these bars bearingon hardened steel balls 17 each adapted to roll on a circular hardenedsteel bearing plate 19 mounted on the upper end of a stand 21 having anannular wall 23 surrounding the bearing plate 19, and extending upwardthereabove forming an oversize socket for the ball 17 (see particularlyFIG. 14). The wall 23 has a brass ring 25 as a liner, and a sheet metalring 27 extending upward therefrom around its outside with an inwardlydirected annular flange 29 at the upper end of the ring. The ball stands21 are mounted on the upper flanges of a pair of I- beams 31 extendingalong ledges 33 on opposite sides of an elongate pit 35 in a concretefoundation 37. The carriage 5, bearing on the balls 17, is adapted tooscillate circularly in a horizontal plane via rolling of the balls 17around on the plates 19 within the annular walls 23, and means such asindicated at 39 is provided for circularly orbiting the carriage in thestated horizontal plane. As shown in FIGS. 1, 2, 6 and 7, this meanscomprises an electric motor 41 driving via a belt and pulley drive 43the input shaft 45 of a first speed reducer 47 at one end of theapparatus. A drive shaft 49 extends from input shaft 45 to the inputshaft 51 of a similar speed reducer 53 at the other end of theapparatus. Each speed reducer has an output shaft 55 extending upwardtherefrom. Secured on a circular flange 57 at the upper end of each ofshafts 55 is a circular flange 59 having an eccentrically located crankpin 61 extending upwardly therefrom with its upper end in a bearing 63mounted on the bottom of the carriage in position between theintermediate longitudinal bars 7 of the carriage 5. The arrangement issuch that on operation of the motor 41, the crank pins 61 are rotated byshafts 55 in a circle about the vertical axes of the latter to effectcircular orbiting of the carriage 5 with the circular orbit having aradius equal to the eccentricity of the pins 61 relative to the shafts55. The motor 41 is mounted on a platform 65 (FIG. 7) adjacent one ofthe l-beams 31 on the inside thereof, and the speed reducers 47 and 53are mounted on vertical plates 67 on the inside of an intermediateI-beam 69 secured to the other l-beam 31 as indicated at 71. Each of theshafts 55 is provided with a counterbalance 72.

The vacuum table 1 has a double bottom generally designated 73comprising an imperforate bottom plate 75 and a perforate top plate 77.The perforations in the latter are indicated at 79. These perforationsmay be of 3/l6 inch diameter, with 30 perforations per square foot ofarea of the plate. The space between the plates 73 and 75 constitutes avacuum chamber VC in which a vacuum is adapted to be drawn via a vacuumline VL (diagrammatically represented in FIG. having a solenoid-operatedvacuum valve VL (see also FIG. 8) therein, this line being connected toa suitable evacuating means. Line VL includes a flexible portionconnected to the table to accommodate the oscillation and tilting of thetable.

The bottom plate 75 is mounted on a base frame generally designated 80.The table has a rim generally designated 81 extending upwardly along oneside, its end opposite the hopper and its other side, and is open at itshopper end. This rim 81 is formed by vertical plates 83 extending upfrom the sides of the double bottom and a vertical plate 85 extending upfrom the opposite end of the bottom, and is provided to retain theaforesaid slurry and graining balls 3 on the table.

The hopper 4 (see particularly FIGS. 4 and 5) has a bottom generallydesignated 87, side walls each designated 89 and an end wall 91 at oneend, being open at its other end. The side walls 89 are constituted bymetal plates having bottom edges 93 (see FIG. 5) which slant up towardtheir top edges from a deep section of the side plates adjacent end wall91. The bottom 87 comprises a metal plate welded at its side edges tothe side plates 89 just above and generally parallel to said bottomedges 93. This bottom plate, which has downwardly directed end flanges95 and 97 for reinforcement, terminates short of end wall 91, which isconstituted by a plate extending between and welded at its sides to theside plates 89, this end plate being bent inward to form a step asindicated at 99 and having a downwardly extending lower margin 101spaced from flange 95 of the bottom plate 87 to provide a drain opening103 extending the full width of the hopper (from one side plate 89 tothe other). A screen 105 is provided for this drain opening, ofsufficiently small mesh as to be capable of retaining properly sizedballs 3 thereon. Angle iron reinforcements such as indicated at 107 arewelded to the end wall extending across the bottom of the step 99adjacent the outer corners of the hopper.

The hopper 4 is provided with a pair of pivot pins 109 extendinglaterally outward from brackets 111 secured to opposite sides of thehopper at its open (shallow) end. These pins are journalled for swingingmovement of the hopper about a horizontal transverse axis at the openend of the table 1 in bearings 113 provided in side bars 115 of aC-shaped frame 117 which projects from the open end of the table. Theside bars 115 of this C- shaped frame, which are of hollow rectangularcross section, are welded on the outside of the vertical side plates 83of the table and extend beyond the open end of the table, the outer endsof these side bars being spanned by an end bar 119 also of hollowrectangular cross section. The hopper is swingable within the C- shapedframe 117 on the horizontal axis of pins 109 relative to the table 1between the lowered level position in which it is shown in solid linesin FIGS. 1, 5 and 8, and the raised uptilted position in which it isshown at HR in phantom lines in FIGS. 1 and 8. In the lowered levelposition of the hopper, which is determined by engagement of the angleirons 107 with pads 121 on hopper supports 123 carried by the end bar119 of the C- shaped frame 117, the upper edges of the side and endwalls 89 and 91 of the hopper are generally horizontal (when the table 1is horizontal) and at a level slightly below the level of the top edgesof the vertical side plates 83 of the table (and the top edges of theframe 1 l7 and the bottom plate 87 of the hopper is inclined downwardlyaway from the open end of the table 1 (which may also be referred to asits head end).

The perforate top plate 77 of the table 1 has a perforate flexible coveror blanket 123, made of a suitable rubber, for example. This blanket hasperforations indicated at 79 registering with perforations 79 in thetable top plate 77 and extends forward over the horizontal leg 125 of anangle iron 127 extending transversely across the table 11 at its openend and thence down over the inclined bottom plate 87 of the hopper soas to close' the gap at 129 between the end edges of plate 87 and theedge of leg 125 of the angle iron 127 (which latter edge is rounded asshown in FIG. 5), so that the bottom of the hopper is in effectcontinuous with while swingable with respect to the table topplate 77.The hopper has a pair of side seal plates 131 (made of urethane, forexample) at its end toward the open end of the table secured to theinside of the hopper side walls 89 and projecting endwise therefrom andwhich have their inside faces in slidable sealing engagement with theoutside faces of back-up plates 133 extending from the table 1, so thatthe sides of the hopper are in effect continuous with while swingablewith respect to the vertical side walls 83 of the table. A trough orsump 135 is provided extending across the table 1 and underneath thetable at its open end to collect slurry which may leak throughperforations 79. Drainage from this sump is via a drain having a valveV2. This is a conventional motor-operated valve, the motor of which isoperated in one direction to close the valve (in order to hold vacuum inchamber VC) and in the opposite direction to open it (to drain offslurry from VC and vent it). Stabilizer bars 137 are provided on theoutside of the hopper side walls 89 adjacent the outer end of thehopper, these bars being slidable on the inside faces of stabilizerplates 139 adjustably mounted as indicated at 141 on the inside of sidebars 115 of the C-shaped frame 117.

Means for raising and lowering the hopper 4 relative to the table isshown to comprise a hydraulic cylinder 143 pivotally mounted asindicated at 145 at one end on a bracket structure 147 which is securedto the bottom of the table 1 adjacent one side thereof. A piston rod 149extends from a piston in the cylinder through the other end of thecylinder and is pin-connected at 151 to the end of a rocker arm 153 on ahorizontal rock shaft 155 which extends transversely across theapparatus having its ends journalled in bearings 157 mounted on thebottoms of the side bars 115 of the C-shaped frame 117. The rock shaft155 has a pair of radial lift arms 159 carrying rollers 161 at theirfree ends engaging bottom rails 163 on the sides 89 of the hopper. Thearrangement is such that on retraction of the piston rod 149, the hopperis lowered relative to the table 1 (as shown in solid lines in FIGS. 1,5 and 8), and on extension of the piston rod, lift arms 159 are swungupward to raise the hopper to its uptilted position HR relative to thetable as shown in phantom in FIGS. 1 and 8 wherein its bottom plate 87is slightly inclined downward toward the head end of the table.Operation of cylinder 143 is under control of a solenoid valve V3 havingan extend solenoid V3a and a retract solenoid V3b.

Means indicated generally at 165 is provided for tilting the table 1 oncarriage 5 to its ball-unloading position BU inclined downwardly towardits hopper or head end (its left end as viewed in FIGS. 1, 5 and 8), andmeans indicated generally at 167 is provided for oppo sitely tilting thetable to its ball-loading position BL inclined downwardly away from itshopper end. As shown best in FIGS. 2 and 8, the means 165 for tiltingthe table to its ball-unloading position BU comprises a hydrauliccylinder 169 pivoted as indicated at 171 at one end on a bracket 173secured to the carriage 5 adjacent its center. A piston rod 175 extendsfrom a piston in cylinder 169 through the other end of the cylinder andis pin-connected at 177 to a rocker arm 179 on a horizontal rock shaft181 extending transversely of the carriage therebelow and journalled atits ends in bearings 183 at the sides of the carriage 5. A pair of liftarms 185 extending radially from the rock shaft 181 have rollers 187 attheir free ends engaging the bottom of the table bottom frame 80.Operation of cylinder 169 is under control of a solenoid valve V4 havingan extend solenoid V4la and a retract solenoid V4b (see FIG. 8).

The means 167 (see particularly FIGS. 2 and 8) for tilting the table toits ball-loading position BL inclined downwardly away from its hopperend is similar to means 165, comprising a hydraulic cylinder 217 pivotedas indicated at 219 at one end on bracket 173 oppositely to cylinder169, with piston rod 221 extending from a piston in the cylinder 217through the other end of the cylinder pin-connected at 223 to a rockerarm 225 on a horizontal rock shaft 227 extending transversely of thecarriage 5 therebelow and journalled at its ends in bearings 229 at thesides of the carriage 5. A pair of lift arms 231 extending radially fromthe rock shaft 227 have rollers 233 at their free ends engaging thebottom of the table bottom frame 80. Operation of cylinder 217 is undercontrol of a solenoid valve V6 having an extend solenoid V6a and aretract solenoid V6b (FIG. 8).

For tilting the table 1 to its ball-loading position BL, the table ispivoted for swinging movement on a horizontal axis adjacent its end awayfrom the hopper (which may be referred to as its foot end). For thispurpose, a table foot pivot rod 191 is provided extending horizontallytransversely of the carriage 5 under the foot end of table 1, spacedslightly outward from the foot end of the carriage. Rod 191 is mountedin brackets 193 secured to the foot end of the carriage. The table has apair of legs 195 extending downwardly from its bottom at opposite sidesthereof adjacent its foot end having semicircular recesses 197 at theirlower ends receiving the rod adjacent the ends of the rod. Pivoted at199 on each leg 195 is a gripper or lock 201 having a semicircularrecess 203 adapted to receive the rod below the lower end of the leg.Each gripper or lock 201 is adapted to be swung by a hydraulic cylinder205 between the closed locking position in which it is illustrated inFIG. 11 cooperable with the lower end of the leg 195 for locking thetable to the carriage and for pivoting the table for swinging movementabout the axis of the rod (with the table locked to the rod), and theretracted open position shown in FIG. 12 wherein it is wholly clear ofthe rod. Each cylinder 205 is pivoted at one end as indicated at 207 ona bracket 209 mounted at the foot end of the table. The piston rod 213of each cylinder extends out of the other end of the cylinder to a pinconnection at 215 with the respective gripper 201. Operation ofcylinders 205 is under control of a solenoid valve V5 having an extendsolenoid V5a and a retract solenoid V5b (FIG. 8). For tilting the table1 to its ball-unloading position BU, the table is pivoted for swingingmovement on a horizontal axis adjacent its hopper or head end, and forthis purpose a head pivot rod 235 is provided extending horizontally andtransversely of the carriage 5 under the hopper end of table 1, spacedslightly outward from the head end of the carriage. Rod 235 is mountedin brackets 237 secured to the head end of the carriage. The table has apair of legs 239 (like legs 195) extending downwardly from its bottom atopposite sides thereof adjacent its head end having semicircularrecesses 241 at their lower ends receiving the rod 235 adjacent the endsof the rod. Pivoted at 243 on each leg 239 is a gripper or lock 245(like grippers 201) having a semicircular recess 247 adapted to receivethe rod 235 below the lower end of the leg. Each gripper or lock 245 isadapted to be swung by a hydraulic cylinder 249 between a closed lockingposition (corresponding to the closed position of grippers 201)cooperable with the lower end of the leg 239 for locking the table tothe carriage and for pivoting the table for swinging movement about theaxis of the rod 235 with the table locked to the rod, and a retractedopen position (corresponding to the retracted position of grippers 201)wherein it is wholly clear of the rod. Each cylinder 249 is pivoted atone end as indicated at 251 on a bracket 253 extending down from thebottom of the table at its head end. The piston rod 255 of each cylinder249 extends out of the other end of the cylinder to a pin connection at257 with the respective gripper or lock 245. Operation of cylinders 249is under control of a solenoid valve V7 having an extend" solenoid V7aand a retract solenoid V7b.

The above described arrangement is such that with the grippers or locks201 unlocked and grippers or locks 245 locked on rod 235, the table 1may be tilted to its ball-unloading position BU by actuation of cylinder169 to extend the piston rod 175, thereby to rock the shaft 181 and arms185 counterclockwise as viewed in FIG. 2 to tilt the table upwardlyabout the axis of rod 235. With the grippers or locks 245 unlocked andgrippers or locks 201 locked on rod 191, the table may be tilted to itsball-loading position BL by actuation of cylinder 217 to extend pistonrod 221, thereby to rock shaft 227 and arms 231 clockwise as viewed inFIG. 2 to tilt the table upwardly about the axis of rod 191.

The table 1 has stabilizers 259 extending downwardly at the sidesthereof on the outside of and slidably engageable with bronze pads 261mounted at the sides of the carriage 5. These stabilize the table whenit is tilted to its ball-unloading position BU and also when it istilted to its ball-loading position BL, as well as when the table isdown in its level position. Both sets of grippers 201 and 245 areadapted to be locked to their respective rods when the table is down inits level position for locking the table to the carriage.

A spray pipe 263 is mounted in suitable manner extending transverselyacross and above the table 1 adjacent its foot end, and another suchpipe 265 extends transversely across and above the table adjacent itshead end. These pipes are secured to the table in any suitable manner soas to move therewith when the table is tilted. Pipe 263 is adapted tospray water downwardly on the table, and pipe 265 is adapted to spraywater downwardly into the hopper. Flexible water hose lines (not shown)are connected to these pipes with the delivery of water thereto undercontrol of solenoid valves V8 and V9, respectively (see FIG. 8). A spraypipe 271 is provided within the table between plates 75 and 77 at itsfoot end for spraying water out over the bottom or bed plate 75. Thisalso is supplied via a flexible hose line (not shown) under control ofasolenoid valve V10.

The sequence of operation of the apparatus is under control of a systemof limit switches illustrated in FIG. 8. A first limit switch LS1 ispositioned for actuation by the piston rod 255 of one of the cylinders249 when retracted to open grippers 24S, and for deactuation when thispiston rod is extended to close the grippers 245. A second limit switchLS2 is positioned for actuation by the stated piston rod 255 whenextended to close the grippers 245, and for deactuation when this pistonrod is retracted. A third limit switch LS3 is positioned for actuationby the piston rod 213 of one of cylinders 205 when retracted to opengrippers 201, and for deactuation when this rod is extended to close thegrippers 201. A fourth limit switch LS4 is positioned for actuation bythe piston rod 213 when extended to close grippers 201, and fordeactuation when this rod is retracted. A fifth limit switch LS5 ispositioned for actuation by arm 179 when the table 1 is tilted to itsball-unloading position BU, and a sixth limit switch LS6 is positionedfor actuation by arm 179 when the table is brought back down to itslevel position TL. A seventh limit switch LS7 is positioned foractuation by arm 225 when the table is tilted to its ball-loadingposition BL, and an eighth limit switch LS8 is positioned for actuationby the arm 225 when the table is brought back down to its level positionTL. A ninth limit switch LS9 is positioned for actuation by arm 153 whenthe hopper 4 is raised. The contacts of these limit switches (and thecontacts of other switches and certain relays of the apparatus) areshown in (FIGS. 13A-C in the positions occupied when the apparatus is atrest between cycles of operation, and subsequent references to contactsas being normally open or normally closed refers to their status whenthe apparatus is at rest between cycles.

Now referring to FIGS. 13A-C, first more particularly to FIG. 13A, theapparatus is shown as being supplied with electrical power via athree-phase supply including lines L1, L2 and L3. A main switch for thissupply is indicated at 275. The motor 41 for oscillating the carriage 5and the table 1 has a winding (not specifically shown) for slow-speedoperation thereof fed off lines L1, L2 and L3 under control of a set ofcontacts RSa (FIG. 13A) of a slow-speed motor relay RS (FIG. 13B) and awinding (not specifically shown) for highspeed operation thereof fed offlines L1, L2 and L3 under control of a set of contacts RFa (FIG. 13A) ofa high-speed motor relay RF (FIG. 133). Lines L1 and L2 feed the primaryof a step-down transformer T, the secondary of which feeds power linesL4 and L5.

A normally open Run switch 277, a normally closed Stop switch 279, anormally open switch A and the coil of a control relay CR1 are connectedin series across lines L4 and L5 in a line 281. Switch A is a loadswitch of a stepping switch 283, such as one sold under the trademarkAGASTAT by the Agastat Division of Elastic Stop Nut Corporation ofAmerica, of Elizabeth, New Jersey. Generally, this stepping switch isone having a rotary programming drum and a motor 285 for indexing thedrum in steps, with pins on the drum for actuating a plurality ofso-called load switches A-P in a programmed sequence (determined by thedisposition of the pins in the drum). The drum also carries a movablecontactor indicated at 287 in FIG. 13A sequentially engageable witheighteen fixed contacts on stepping of the drum by the motor. Thecontactor 287, which steps counterclockwise as shown in FIG. 13A, is

shown in its home position on the first of these contacts of contacts isconnected in parallel with the Run switch 277 via a line 289 connectedto a junction 291 in line 281 between the Run switch 277 and the Stopswitch 279. A line 293 interconnects this junction 291 and the firstcontact of the stepping switch 283. A Run" lamp 295 is connected inparallel with the Stop" switch 279, load switch A and relay CR1 via aline 297. The stepping switch 283 includes a relay R1 adapted whenenergized to close a set of normally open contacts Rla, and furtherincludes a limit switch S2 for maintaining the stepping switch motor 285energized for an indexing interval (e.g., of rotation of 287). The coilof relay R1 and limit switch S2 are connected in series across lines L4and L5 in a line 299. The movable contactor 287 of the stepping switch283 is connected via a line 301 to a junction 303 in line 299 betweenthe limit switch S2 and relay R1. Contacts Rla and motor 285 areconnected in series in a line 305 shunted around limit switch S2 and thecoil of relay R1.

A line L6 including one set of contacts 307a of a double-throw selectorswitch 307 extends from line 293. A line L7 including the other set ofcontacts 307b of switch 307 parallels line L6. The switch 307 is adaptedfor closure of its contacts 307a to energize L6 for automatic operationof the apparatus and, alternately, for closure of its contacts 307!) toenergize L7 for manual operation of the apparatus. A line 309 includinga pressure switch PS-A is connected between line L6 and the secondcontact of the stepping switch 283. This pressure switch isinterconnected with the vacuum chamber VC of the table 1 and is adaptedto close when a predetermined vacuum has been drawn in chamber VC. A

lamp 311 for signalling that the vacuum has been drawn in chamber VC isconnected in series with the pressure switch in a line 313 between line309 and line L5. Contacts LS7b and LS9a of the aforesaid limit switchesLS7 and LS9 are connected in series with one another to the thirdcontact of stepping switch 283 in a line 315 (see FIGS. 13A and B). AtTD1 (FIG. 13B) is indicated a time delay relay having a set of normallyopen contacts TDla (FIG. 13A) connected in a line 317 between line L6and the fourth contact of stepping swtich 283. A manual Start Grainingswitch 319 is connected in a line 321 in parallel with contacts TDla.Normally closed contacts LS2b of limit switch LS2 are connected to thefifth contact of stepping switch 283 in a line 323. At TD2 (FIG. 13B) isindicated a motordriven timer having a set of normally open contactsTD2a (FIG. 13A) connected in a line 325 between line L6 and the sixthcontact of stepping switch 283. Normally open contacts LS5b of limitswitch LS5 are connected to the seventh contact of stepping switch 283in a line 327. At TD3 (FIG. 13B) is indicated a time delay relay havinga set of normally open contacts TD3a (FIG. 13A) connected in a line 329between line L6 and the eighth contact of stepping switch 283. Asocalled Shake-off Complete switch 331 is connected in a line 333 inparallel with contacts TD3a. Contacts LS10b of a limit switch LS10 areconnected to the ninth contact of stepping switch 283 in a line 335. AtTD4 (FIG. 13C) is indicated a time delay relay having a set of contactsTD4a connected in a line 337 between line L6 and the tenth contact ofstepping switch 283. A Lower Table" switch 339 is connected in a line341 between line L6 and the eleventh contact of stepping switch 283.Contacts LS4b of limit switch LS4 are connected to the twelfth contactof stepping switch 283 in a line 343. The thirteenth to the eighteenthcontacts of stepping switch 283 are interconnected together as indicatedat 345, and are interconnected with line L4 by a line 347.

A load switch I (FIG. 13A) of stepping switch 283 is connected in serieswith a Lower Table" lamp 349 between lines L6 and L5 via a line 351.Load switch K (FIG. 13B) of stepping switch 283 is connected in serieswith a "Ready lamp 351 between lines L4 and L5 via a line 353. Loadswitch L of stepping switch 283 is connected in series with a Complete"lamp 355 between lines L4 and L5 via a line 357. Load switch M ofstepping switch 283 is connected in series with normally closed contactsRSb of relay RS, the coil of relay RF and a set of overload switches 359between lines L6 and L5 via a line 361. Load switch N of stepping switch283 is connected in series with normally closed contacts RFb of relay RFand the coil of relay RS in a line 363 in parallel with M, RSb and RF.

The motor of the motor-operated sump valve V2 has a winding 365 foroperating the motor in the direction to close the valve and a winding367 for operating the motor in the opposite direction to open the valve.The valve includes a limit switch LS10 actuated to stop the motor whenthe valve opens and a limit switch LS1l actuated to stop the motor whenthe valve closes. The latter has normally closed contacts LSlla andnormally open contacts LSllb. Normally open contacts B1 of a load switchB of the stepping switch 283, contacts LSlla and winding 365 areconnected in series across lines L4 and L5 in a line 369. Normallyclosed contacts B2 of load switch B are series-connected with normallyopen contacts LS10a of limit switch LS10 and motor winding 367 in a line371 in parallel with Bl, LSlla and 365. Contacts B1 and LSllb areconnected in series across lines L4 and L5 with the solenoid of thevacuum valve V1 via a line 375. Contacts B2 and LSlOb areseries-connected between line L4 and the ninth contact of steppingswitch 283 via the aforesaid line 335 (FIG. 13A).

A load switch G of the stepping switch 283 is seriesconnected withnormally closed contacts LSla of limit switch LS1 and the retractsolenoid V7b of valve V7 for cylinders 249 in a line 377 across lines L6and L5. Normally open contacts LSlb of limit switch LS1 areseries-connected with normally closed contacts LS7a and the extendsolenoid V6a of valve V6 for cylinder 217 in a line 379 in parallel withLSla and V7b. Normally open contacts LS7b of LS7 and normally opencontacts LS9a of limit switch LS9 are seriesconnected with G and LSlbbetween line L6 and the third contact of stepping switch 283 via theaforesaid line 315. Normally closed contacts LS9b of limit switch LS9are series-connected with the extend solenoid V3a of valve V3 forcylinder 143 and with G and LSlb across lines L6 and L5 via a line 381.

Load switch J of stepping switch 283 is seriesconnected with the coil oftime delay relay TD1 across lines L6 and L5 in a line 383. Load switch Fof switch 283 is series-connected with normally open contacts LS8a oflimit switch LS8, normally closed contacts 385a of a manually operableReset Plates switch 385 and the retract solenoid V6b of valve V6 forcylinder 217 in a line 387 across lines L6 and L5. Normally opencontacts 385b of manual switch 385 are connected in a line 389interconnecting line L7 to line 387 between 385a and V6b. Normallyclosed contacts LS8b The motor of the motor-driven timer TD2 isindicated at 393, an electric clutch of this timer is indicated at 395,and a normally closed set of contacts of this timer is indicated atTD2b. These contacts open, and the previously mentioned contacts TD2a(FlG. 13A) close, when the timer TD2 has timed out a predetermined timeinterval. Normally open contacts RFc of relay RF are series-connectedwith contacts TD2b and motor 393 in a line 397 across lines L6 and L5.Load switch of stepping switch 283 is series-connected with clutch 395in a line 399 across lines L4 and L5.

Load switch 1 of stepping switch 283- is seriesconnected with normallyclosed contacts LS3a of limit switch LS3 and the retract solenoid Vb ofvalve V5 for cylinders 205 via a line 401. Normally open contacts LS3bof limit switch LS3 are series-connected with normally closed contactsLS5a of limit switch LS5 and the extend" solenoid V4a of valve V4 forcylinder 169 in a line 403 in parallel with LS3a and VSb. Normally opencontacts LS5b of limit switch LS5 are series-connected with I and LS3bbetween line L6 and the seventh contact of stepping switch 283 via theaforesaid line 327. The retract solenoid V3b of valve V3 for cylinder143 is connected in a line 405 in parallel with LS5a and V4a.

The coil of time delay relay TD3 is series-connected with load switch Dof stepping switch 283 across lines L6 and L5 via a line 407. Thesolenoid of the hopper spray valve V9 is connected in parallel with theTD3 coil via a line 409. The load switch C of stepping switch 283 isseries-connected with the coil of a time delay relay TDS across lines L6and L5 via a line 411. Normally closed contacts TD5a of relay TD5 areseriesconnected with the plate spray solenoid valve V8 in a line 413 inparallel with TD5.

Load switch E (FlG. 13C) of stepping switch 283 is series-connected withthe coil of time delay relay TD4 across lines L6 and L5 via a line 415.The bed spray solenoid valve V is connected in parallel with TD4 via aline 417. Load switch H of stepping switch 283 is series-connected withnormally open contacts LS6a of limit switch LS6 and the retract solenoidV4b of valve V4 for cylinder 169 across lines L6 and L5 via a line 419.Normally closed contacts LS6b of limit switch LS6 are series-connectedwith normally open contacts LS4a of limit switch LS4 and the extendsolenoid V5a of valve V5 for cylinders 205 in a line 421 in parallelwith LS6a and V4b. Normally closed contacts LS4b of limit switch LS4 areseries-connected with switch H and contacts LS6b between line L6 and thetwelfth contact of stepping switch 283 via the aforesaid line 343.

FIG. 15 is a chart showing the programming of the stepping switch 283,in accordance with the stepping of the movable contactor 287 of thisswitch from contact to contact. The numbers in the first column of thechart refer to the eighteen contacts or positions of the steppingswitch. The references in the third column of the chart are to theelements the operation of each of which effects the stepping of themovable contactor 287 from contact to contact. For example, operation ofthe Run switch 277 effects stepping of movable contactor 287 from thefirst to the second contact of the stepping switch 283 (as will appear).The fourth column shows the state of the load switches A-P of steppingswitch 283 for each step of the latter, X" indicating actuation of eachrespective load switch, and 0" indicating deactuation of the loadswitch. For example, with movable contactor 287 on the first contact ofthe stepping switch 283 (step 1 on the chart), load switches A and K areactuated and the remainder are deactuated; with 287 on the secondcontact of 283 (step 2 on the chart), load switches A and B are actuatedand the remainder of the load switches are deactuated. The commercialstepping switch 283 which has been used is an eighteen-contact switchwith twenty load switches A-T. Load switches Q-T of the stepping switch283 are not used, and the thirteenth to the eighteenth contacts areinterconnected as indicated at 345 in FIG. 13A for homing of the movablecontactor 287 (i.e., for movement of 287 back to the first contact) whenit steps off the twelfth contact. Operation is as follows:

For automatic operation of the apparatus, the selector switch 307 is setto close contacts 307a, whereby, with the main power switch 275 closed,line 6 is energized as well as line 4. At the start of any cycle ofoperation, the table 1 is down in its level position indicated at TL inFIG. 8. Grippers 201 and 245 are in their closed locking position. Thehopper 4 is down in its lowered level position. Balls 3 are in thehopper. Operation then proceeds in steps as follows (refer also to FIG.15):

STEP 1 Rectangular aluminum plates 2 to be grained are placed on theblanket 123 of the table 1. Substantially the entire area of the blanketmay be covered with plates, with adjacent edges of adjacent plates incontiguous relation. The plates may be of various sizes. Plates ofvarious gages may be processed. The timer TD2 is set for the grainingtime desired and the Run" switch 277 is actuated to start a cycle.

STEP 2 On actuation of the Run switch 277, relay CR1 is energized toclose its contacts CRla, thereby closing line 289 to provide a holdingcircuit around switch 277. Relay CR1 is energized via load switch A ofstepping switch 283, this switch A being closed throughout the excursionof the movable contactor 287 of the stepping switch over the first 13contacts of the latter (see FIG. 15). Lamp 295 is illuminated to signalthat the apparatus is running. Also on actuation of the Run" switch 277,a circuit is closed for relay R1 via line 293, the first contact and themovable contactor 287 of stepping switch 283, and lines 301 and 299.Relay contacts Rla close and this energizes the stepping switch motor285 to step 287 to the second contact of 283 and actuate load switch B,closing contacts B1 in line 369 and opening contacts B2 in line 371.With contacts B1 and LS11a closed in line 369, coil 365 of the motor foroperating valve V2 is energized to close valve V2. When it closes,contacts LSlla open, stopping the motor and contacts LS1 1b close toenergize and open the vacuum valve V1 via line 375. Limit switch LS10 isdeactuated so that its contacts LSlOa (line 371) close and its contactsLSlOb (line 335) open. With valve V2 closed and valve V1 open, a vacuumis drawn in vacuum chamber VC and this results in vacuum gripping of theplates 2 on blanket 123 of the table 1. When the vacuum drawn in chamberVC reaches a predetermined value, the pressure switch PS-A (which isresponsive to vacuum in VC) closes. Relay R1 is energized via lines 309,the second contact and the movable contactor 287 of stepping switch 283and lines 301 and 299, with resultant energization of motor 285 to stepthe movable contactor 287 to the third contact of switch 283 and closeload switches G and N (A and B remaining closed) to initiate STEP 3 Onclosure of load switch N (with contacts RFb closed), relay RS isenergized to close contacts RSa thereby initiating operation of motor 41to oscillate the carriage 5 and table 1 carried by the carriage at lowspeed. On closure of load switch G (with contacts LSla closed) theretract solenoid V7b of valve V7 is energized to retract the piston rodsof the hopper end lock cylinders 249, thereby opening the hopper endgrippers or locks 245. This results in actuation of limit switch LS1,opening its contacts LSla and closing its contacts LSlb. The grippers orlocks 201 at the foot end of the table remain locked to the rod 191. Onclosure of contacts LSlb (and with load switch G and contacts LS7aclosed), a circuit is completed through the extend" solenoid V6a ofvalve V6 for cylinder 217 and the piston rod of this cylinder isextended to swing the table 1 upward about the axis of rod 191 to theballloading position BL. Contacts LS9b being closed at this time, acircuit is also completed through the extend solenoid V3a of valve 3 forthe hopper-operating cylinder 143, and the piston rod of this cylinderis extended to swing the hopper 4 upward to its raised position relativeto the table 1 indicated at HR in FIGS. 1 and 8. With the table 1 in itsball-loading position BL, and with the hopper 4 in its raised positionHR relative to the table, and with the table and hopper continuouslyoscillating, the balls 3 are discharged from the hopper onto the tableover the plates 2 on the table. On swinging of the table by cylinder 217to position BL, limit switch LS7 is actuated, and on raising of thehopper by cylinder 143, limit switch LS9 is actuated. Thus, contactsLS7a are opened to deenergize solenoid V6a, contacts LS9b are opened todeenergize solenoid V3a, terminating step 3. Contacts LS7b and LS9a inline 315 close to energize relay R1 via line 315, the third contact andmovable contactor 287 of stepping switch 283, and lines 301 and 299,thereby energizing motor 285 to step the movable contactor 287 to thefourth contact of switch 283 and to close the load switch J (switches A,B, G and N remaining closed). This initi- STEP 4.

On closure of load switch .1 (in line 383), time delay relay TDl isenergized, and after it has timed out its predetermined time interval,closes its contacts TDla in line 317. The table 1 (in its ball-loadingposition) and the hopper 4 (in its raised position) continue tooscillate at low speed during this time interval to shake the balls 3out of the hopper and deliver them onto the table 1 over the plates 2 onthe table. Closure of contacts TDla at the end of this shake-outinterval energizes relay R1 via line 317, the fourth contact and movablecontactor 287 of switch 283, and lines 301 and 299, thereby energizingmotor 285 to step the movable contactor 287 to the fifth contact ofswitch 283 and closing load switch F and opening load switches G and J,with load switches A, B and N remaining closed.

STEP 5 On closure of load switch F, and with contacts L580 closed (limitswitch LS8 having been deactuated in Step 3 on extension of the pistonrod of cylinder 217), the retract solenoid V6b of valve V6 for cylinder217 is energized, and the piston rod of this cylinder is retracted tolower the table 1 to its level position TL, the hopper 4 remaining inits raised position HR. When the table reaches its lowered position,limit switch LS8 is actuated to open LS8a and close LS8b. With contactsLS2a closed and LS2b open as a result of the retraction of the pistonrods of cylinders 249 to open grippers 245 during Step 3, on closure ofcontacts LS8b the extend solenoid V7a of valve V7 for cylinders 249 isenergized to extend the piston rods of cylinders 249 to cause thegrippers 245 to close on the rod 235 and thus lock the hopper end of thetable 1 to the carriage 5. Extension of the piston rods of cylinders 249actuates limit switch LS2 (and deactuates LS1), opening contacts LS2aand closing contacts LS2b. On closure of contacts LS2b in line 323,relay R1 is energized via line 323, the fifth contact and movablecontactor 287 of switch 283 and lines 301 and 299, with resultantenergization of motor 285 to step the movable contactor 287 to the sixthcontact of switch 283, closing load switches M and O and opening loadswitch N (A and B still remaining closed) to initiate STEP 6.

The table 1 is now down in its level position, with the balls 3 spreadout over the plates 2 (held flat by vacuum on the blanket 123 of thetable). The hopper is up in its raised HR position to keep the balls outof the hopper and to contain slurry on the table. On closure of loadswitch M (in line 361), and with contacts RSb closed as a result of theopening of load switch N and deenergization of relay RS to closecontacts RSb in line 361, relay RF is energized, closing contacts RFa tooperate motor 41 at high speed (and opening contacts RFb in line 363).The abrasive slurry, which may comprise fine silica sand in water, forexample, is poured on to the table, generally to a depth covering theballs, and with the table oscillating at high speed on account of thehigh speed operation of motor 41, the balls and slurry abrade the uppersurfaces of plates 2 to effect the graining thereof. This grainingoperation (i.e., the highspeed oscillation of the table in levelposition with the balls and slurry therein, and with the hopper 4raised) continues for a graining period determined by the setting of thetimer TD2. On closure of the load switches M and O initiating this Step6, contacts RFc in line 397 close to start the motor 393 of this timerin operation and the timer clutch in line 399 is energized via switch 0.When the timer has timed out its preset graining time interval, contactsTD2b open, deenergizing the timer motor 393, and contacts TD2a in line325 close to energize relay R1 via line 325, the sixth contact andmovable contactor 287 of switch 283 and lines 301 and 299, withresultant energization of motor 285 to step the movable contactor 287 tothe seventh contact of switch 283, and opening load switches M and O andclosing load switches l and N (A and B remaining closed) to initiateSTEP 7.

On opening of load switch M and closure of switch N, the motor 41reverts to low speed operation (on account of deenergization of relay RFin line 361 and energization of relay RS in line 363). On opening ofload switch 0, the timer clutch 395 is deenergized. On closure of loadswitch I, with contacts LS3a closed in line 401, the retract solenoidV5b of valve V5 for cylinders 205 is energized to retract the pistonrods of these cylinders and thereby open the grippers 201 at the foot(right) end of the apparatus. When these grippers reach their openposition, limit switch LS3 is actuated to open its contacts LS3a andclose its contacts LS3b in line 403, and limit switch LS4 is deactuated.On closure of contacts LS3b, and with contacts LS5a closed (and LSSbopen), the extend solenoid V4a of valve V4 for the ball-unloadingcylinder 169 is energized to extend the piston rod of this cylinder toswing the table 1 about the axis of rod 235 to its ball-unloadingposition BU. At the same time, the retract" solenoid V3b of valve V3 forthe hopper-operating cylinder 143 is energized to retract the piston rodof this cylinder and thereby lower the hopper 4 down to its levelposition relative to the table (shown in solid lines in FIGS. 1 and 8).With the table tilted up in its ball-unloading position BU, and thehopper 4 level with the table, the balls 3 roll down off the plates 2into the hopper, and the slurry flows down off the plates into thehopper and drains out through the hopper drain screen 105. It will beunderstood that suitable drainage facilities are provided underneath thehopper to drain away the slurry from the hopper. The screen used at 105is one with a mesh ofa size to hold balls of the desired diameter, butto pass undersized balls, which drain out with the slurry. It will beobserved that the table 1 and hopper 4 are oscillating throughout thisball-unloading and slurry-draining Step 7. On extension of the pistonrod of cylinder 169 to tilt the table up to its ball-unloading positionBU, limit switch LS5 is actuated (and LS6 is deactuated) with resultantopening of its contacts LSSa and closure of its contacts LSSb in line327. With the latter contacts closed, relay R1 is energized via line327, the seventh contact and movable contactor 287 of switch 283andlines 301 and 299 with resultant energization of motor 285 to stepthe movable contactor 287 to the eighth contact of switch 283, and toclose load switches C and D, with load switches A, B, I and N remainingclosed, to initiate STEP 8.

With load switches A, B, l and N remaining closed, the table remains inits ball-unloading position BU with the hopper 4 tilted up, andcontinues to oscillate at low speed. On closure of load switches C and D(in lines 411 and 407, respectively) time delay relays TD5 and TD3 andthe plate spray and hopper spray solenoid valves V8 and V9 are energizedand thus opened to discharge sprays of water down on the plates 2 on thetable and down on the balls 3 in the hopper 4 to wash off the plates andthe balls. The wash water drains out through hopper drain screen 105.After relays TD5 and TD3 have timed out their predetermined timeintervals, relay TDS opens its contacts TDSa (line 413) and relay TD3closes its contacts TD3a. With the latter contacts closed, relay R1 isenergized via line 329, the eighth contact and movable contactor 287 ofswitch 283 and lines 301 and 299 with resultant energization of motor285 to step the movable contactor 287 to the ninth contact of switch283, and to close load switch L and open load switches B, C, D, l and N,load switch A remaining closed, to initiate STEP 9,.

On closure of load switch L (line 357), lamp 355 is energized to signalthat the ball unloading and the spraying operations have been completed.On opening of load switch B (i.e., opening of contacts B1 and closure ofcontacts B2) and with contacts LS10a closed (and LS10b open) from Step2, coil 367 of the motor for operating the valve V2 is energized to openthis valve for drainage of the sump. When it opens, LSl0 is actuated toreopen LS10a and close LS10b and LSll is deactuated to reclose LSlla andopen LSllb. Also on opening of B1, vacuum valve V1 is deenergized to cutoff the vacuum in the chamber VC. On opening of load switch C, the platespray valve V8 is deenergized and closes to cut off the plate spray, andon opening of load switch D, the hopper spray valve V9 is deenergizedand closes to cut off the hopper spray. On opening of load switch I, thecircuit for solenoids V5b, V4a and V3b is broken, and on opening of loadswitch N, relay RS is deenergized to open contacts RSa (FIG. 13A) andstop the main motor 41 to stop the oscillation of the table. Withcontacts LS10b closed, relay R1 is energized via line 335, the ninthcontact and movable contactor 287 of switch 283 and lines 301 and 299with resultant energization of motor 285 to step the movable contactor287 to the tenth contact of switch 283, and to close load switch E, loadswitches A and L remaining closed, to initiate STEP 10.

With load switch E closed, relay TD4 is energized, and solenoid valveV10 is energized to open to discharge sprays of water via pipe 271 onthe bed plate of the table. This flushes any slurry which may haveleaked through the holes 79 to the sump 135, from which it drains outthrough the open valve V2 (remaining open from Step 9). After timing outits delay, relay TD4 closes its contacts TD4a in line 337 (FIG. 13A) andenergizes relay R1 via line 337, the tenth contact and the movablecontactor 287 of switch 283 and lines 301 and 299 with resultantenergization of motor 285 to step the movable contactor 287 to theeleventh contact of switch 283, and to open load switch E and close loadswitch P, load switches A and L remaining closed, to initiate STEP 11.

With load switch E open, the bed spray valve V10 and relay TD4 aredeenergized. With load switch P closed, lamp 349 is energized toindicate that the graining of the plates 2 has been completed and that,after removing them from the table 1, the latter is to be lowered. Thetable remains indefinitely in its ballunloading position BU (from Step7) until the Lower Table switch 339 in line 341 is closed. Relay R1 isthereupon energized via line 341, the eleventh contact and movablecontactor 287 of switch 283 and lines 301 and 299 with resultantenergization of motor 285 to step the movable contactor 287 to thetwelfth contact 17 of switch 283, and to open load switches L and P andclose load switch H, with load switch A remaining closed, therebyinitiating STEP 12.

With load switch H closed, and with contacts LS6a closed and LS6b open(as a result of deactuation of limit switch LS6 in Step 7), the retractsolenoid V4b of valve V4 for cylinder 169 is energized to retract thepiston rod of this cylinder thereby to lower the table 1 from itsball-unloading position BU to its level position TL. When the table islowered, limit switch LS5 is deactuated and limit switch LS6 isactuated, opening its contacts LS6a and closing its contacts LS6b. Withlimit switch LS4 deactuated and its contacts LS4a closed and LS4b openfrom Step 7, the extend solenoid V5a of valve V5 for cylinders 205 isenergized, and the piston rod of this cylinder is extended to effectlocking of the respective grippers 201 on the rod 191. It will beobserved that, with this relocking of grippers 201, all components(except for switch 283) are back in their starting position as outlinedabove at the beginning of the description of the operation of theapparatus. Upon extension of the piston rods of cylinders 205, limitswitch LS4 is actuated to open its contacts LS4a and close its contactsLS4b, and on closure of the latter, relay R1 is energized via line 343,the twelfth contact and the movable contactor 287 of switch 283 andlines 301 and 299 to energize motor 285 to step the movable contactor287 to the thirteenth contact of switch 283. Via energization of relayR1 from line 347, the movable contactor 287 then steps from contact tocontact until it returns home to the first contact of switch 283. Thisends the cycle, with all components now in posi tion to start anothercycle.

Recapitulating the automatic mode of operation of the apparatus, at thestart, the table 1 is in its level position TL locked to the carriage 5at both its ends by grippers 201 and 245, and the hopper 4 is down. Thesump valve V2 is open and the vacuum valve V1 is closed. After plates 2have been placed on the table, and the operation started by actuation ofthe Run switch 277, sump valve V2 is closed and vacuum valve V1 isopened to draw a vacuum in the vacuum chamber VC of the table to holdthe plates on the table. Motor 41 is operated at low speed to oscillatethe table at low speed. The hopper end grippers or locks 245 are openedvia retraction of the piston rods of cylinders 249 and the table istilted up on the axis of rod 191 to its ball-loading position BL viaextension of the piston rod 175 of cylinder 169. The halls are shakenout of the hopper 4 (which is tilted up relative to the table 1) anddelivered to the table to overlie the plates. The table, stilloscillating, is lowered to its level position TL via retraction ofpiston rod 175, and the balls spread out over the plates as indicated inFIG. 3. The hopper stays up to keep the balls out of the hopper. Themotor 41 is then operated at high speed to oscillate the table at highspeed and the slurry is poured on the table to effect abrasion of thesurfaces of the plates on the table via the combined action of the ballsand the slurry. At the end of this abrasion (graining) phase, the motor41 is brought back to low speed operation. The grippers 201 at the footend of the apparatus are unlocked via retraction of the piston rods ofcylinders 2 05, and the table' is tilted up about the axis of rod 235 atits head end to its ball-unloading position BU. The hopper 4 is broughtdown to its lowered position via retraction of piston rod 149 ofcylinder 143. The balls roll down off the table 1 into the hopper 4, andthe slurry flows down into and drains out of the hopper, the tableoscillating at slow speed all the while. Valves V8 and V9 open todeliver water to pipes 263 and 265 to spray off the plates and theballs. These sprays are terminated, motor 41 is deenergized to stop theoscillation of the table, sump valve V2 is opened to dissipate thevacuum in chamber VC and for drainage from the sump and vacuum valve V1is closed. Valve V10 opens to deliver water to pipe 271 to spray off thetable bed plate 75. The plates 2 are removed, the table is brought backdown to its level position, and grippers 201 are relocked.

From the above, it will appear that the loading of the table 1 with theballs 3, and the distribution of the balls over the table (i.e., overthe plates 2 on the table) is automatically and efficiently effected.Also, the unloading of the balls from the table involving their returnto the hopper 4, and the cleaning of the balls and removal of anyundersized balls are automatically and efficiently effected. With thetable 1 being a vacuum table, the plates may be rapidly placed on thetable, and become firmly secured thereto when a vacuum is drawn inchamber VC. The vacuum will hold plates of various sizes andthicknesses, and plates may be and preferably are placed on the tablewith their edges contiguous, and substantially the entire surface areaof the table may be covered with plates for maximum utilization thereof.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

ll. Apparatus for graining plates, such as sheet aluminum plates to beused as lithographic plates, comprising a table to be oscillated in alevel position with balls in a slurry thereon for graining plates heldon the table, said table having perforations therein and means forestablishing a vacuum in said perforations for holding plates on thetable, a hopper for the balls at one end of the table, means mountingthe table for being tilted from its said level position to aball-unloading position inclined downwardly toward its said hopper endfor gravity discharge of balls from the table to the hopper and also forbeing tilted to a ball-loading position inclined downwardly away fromits said hopper end for gravity delivery of balls from the hopper to thetable, means for effecting tilting of the table either to its saidball-unloading or its ball-loading position, said hopper being mountedon the table at said one end thereof for being moved between a loweredposition relative to the table and a raised position relative to thetable and having means for effecting said movement of the hopper betweenits said lowered and raised positions, said apparatus further comprisinga flexible cover overlying said table having perforations therein inregister with said perforations in said table, said cover extending inone piece between said table and said hopper and overlying the bottomsurface of said hopper for providing a continuous surface upon which theballs may roll as said balls are delivered to and from the hopper andfor permitting movement of said hopper relative to the table.

2. Apparatus as set forth in claim I wherein said means for effectingtilting of the table to its ballunloading position comprises first meansfor releasably and pivotally locking the table to the carriage at saidone end of the table and first power means for tilting up the tableabout the axis of said first locking means, said means for effectingtilting of the table to its ballloading position comprising second meansfor releasably and pivotally locking the table to the carriage at theother end of the table and second power means for tilting up the tableabout the axis of the second locking means, each power means comprisinghydraulic cylinder means interposed between the carriage and the table,said first locking means comprising a first pair of locks operated byhydraulic cylinders at said one end of the table, with a first rodsecured to the end of the carriage engageable by these locks, and secondlocking means comprising a second pair of locks operated by hydrauliccylinders at the other end of the table, with a second rod secured tosaid carriage engageable by said second pair of locks, the locks of bothsaid first pair and said second pair of locks each comprising a fixedlocking jaw adapted to bear on its respective rod and a movable jawswingable from a locked position in which it cooperates with itsrespective fixed jaw to surround its respective said rod therebypositively to lock said table to said carriage, and an unlocked positionin which it is clear of said rod thereby to permit tilting of the table.

3. Apparatus for graining plates, such as sheet aluminum plates to beused as lithographic plates, comprising a table adapted to be oscillatedin a generally level position with balls in a slurry thereon forgraining plates held on the table, a hopper for the balls at one end ofthe table, means mounting the table for being tilted from its said levelposition to a ball-unloading position inclined downwardly toward itssaid hopper end for gravity discharge of balls from the table to thehopper and also for being tilted to a ball-unloading position inclineddownwardly away from its said hopper and for gravity delivery of ballsfrom the hopper to the table, means for effecting tilting of the tableeither to its ballunloading position or to its ball-loading position,this last said means comprising first means for releasably and pivotallylocking the table to the carriage at said one end of the table and firstpower means for tilting up the table about the axis of said firstpivotal locking means, said means for effecting tilting of the table toits ball-loading position comprising second means for releasably andpivotally locking the table to the carriage at the other end of thetable and second power means for tilting up the table about the axis ofsaid second pivotal locking means, each power means comprising hydrauliccylinder means interposed between the carriage and the table, said firstlocking means comprising a first pair of locks operated by hydrauliccylinders at said one end of the table, with a first rod secured to saidend of the carriage engageable by these locks, and said second lockingmeans comprising a second pair of locks operated by hydraulic cylindersat the other end of the table, with a second rod secured to saidcarriage engageable by said second pair of locks, the locks of both thefirst pair and the second pair oflocks each comprising a fixed lockingjaw adapted to bear on its respective rod and a movable jaw, saidmovable jaw being swingable from a locked position in which itcooperates with its respective fixed jaw to surround said rod andthereby to positively lock said table to said carriage and an unlockedposition in which it is clear of said rod thereby to permit tilting ofthe table.

1. Apparatus for graining plates, such as sheet aluminum plates to beused as lithographic plates, comprising a table to be oscillated in alevel position with balls in a slurry thereon for graining plates heldon the table, said table having perforations therein and means forestablishing a vacuum in said perforations for holding plates on thetable, a hopper for the balls at one end of the table, means mountingthe table for being tilted from its said level position to aball-unloading position inclined downwardly toward its said hopper endfor gravity discharge of balls from the table to the hopper and also forbeing tilted to a ball-loading position inclined downwardly away fromits said hopper end for gravity delivery of balls from the hopper to thetable, means for effecting tilting of the table either to its saidball-unloading or its ball-loading position, said hopper being mountedon the table at said one end thereof for being moved between a loweredposition relative to the table and a raised position relative to thetable and having means for effecting said movement of the hopper betweenits said lowered and raised positions, said apparatus further comprisinga flexible cover overlying said table having perforations therein inregister with said perforations in said table, said cover extending inone piece between said table and said hopper and overlying the bottomsurface of said hopper for providing a continuous surface upon which theballs may roll as said balls are delivered to and from the hopper andfor permitting movement of said hopper relative to the table. 2.Apparatus as set forth in claim 1 wherein said means for effectingtilting of the table to its ball-unloading position comprises firstmeans for releasably and pivotally locking the table to the carriage atsaid one end of the table and first power means for tilting up the tableabout the axis of said first locking means, said means for effectingtilting of the table to its ball-loading position comprising secondmeans for releasably and pivotally locking the table to the carriage atthe other end of the table and second power means for tilting up thetable about the axis of the second locking means, each power meanscomprising hydraulic cylinder means interposed between the carriage andthe table, said first locking means comprising a first pair of locksoperated by hydraulic cylinders at said one end of the table, with afirst rod secured to the end of the carriage engageable by these locks,and second locking means comprising a second pair of locks operated byhydraulic cylinders at the other end of the table, with a second rodsecured to said carriage engageable by said second pair of locks, thelocks of both said first pair and said second pair of locks eachcomprising a fixed locking jaw adapted to bear on its respective rod anda movable jaw swingable from a locked position in which it cooperateswith its respective fixed jaw to surround its respective said rodthereby positively to lock said table to said carriage, and an unlockedposition in which it is clear of said rod thereby to permit tilting ofthe table.
 3. Apparatus for graining plates, such as sheet aluminumplates to be used as lithographic plates, comprising a table adapted tobe oscillated in a generally level position with balls in a slurrythereon for graining plates held on the table, a hopper for the balls atone end of the table, means mounting the table for being tilted from itssaid level position to a ball-unloading position inclined downwardlytoward its said hopper end for gravity discharge of balls from the tableto the hopper and also for being tilted to a ball-unloading positioninclined downwardly away from its said hopper and for gravity deliveryof balls from the hopper to the table, means for effecting tilting ofthe table either to its ball-unloading position or to its ball-loadingposition, this last said means comprising first means for releasably andpivotally locking the table to the carriage at said one end of the tableand first power means for tilting up the table about the axis of saidfirst pivotal locking means, said means for effecting tilting of thetable to its ball-loading position comprising second means forreleasably and pivotally locking the table to the carriage at the otherend of the table and second power means for tilting up the table aboutthe axis of said second pivotal locking means, each power meanscomprising hydraulic cylinder means interposed between the carriage andthe table, said first locking means comprising a first pair of locksoperated by hydraulic cylinders at said one end of the table, with afirst rod secured to said end of the carriage engageable by these locks,and said second locking means comprising a second pair of locks operatedby hydraulic cylinders at the other end of the table, with a second rodsecured to said carriage engageable by said second pair of locks, thelocks of both the first pair and the second pair of locks eachcomprising a fixed locking jaw adapted to bear on its respective rod anda movable jaw, said movable jaw being swingable from a locked positionin which it cooperates with its respective fixed jaw to surround saidrod and thereby to positively lock said table to said carriage and anunlocked position in which it is clear of said rod thereby to permittilting of the table.